Coordinating Concrete Delivery and Placement

ABSTRACT

Described are a method and system for coordinating the delivery and placement of concrete loads at a job site, and more particularly to adjusting a set time value or value range of the concrete loads, thereby to facilitate finishing or other concrete placement activities. In exemplary embodiments, the adjustments can be made based on an assessment of previously placed concrete loads. The set time values or value ranges of the concrete can be monitored and adjusted to achieve desired properties during installation and/or in its hardened state.

FIELD OF THE INVENTION

The present invention relates to concrete construction processes andsystems, and more particularly to coordinating the set time values orvalue ranges, such as workability or compressive strength windows, ofconcrete loads delivered to and placed at a job site.

BACKGROUND OF THE INVENTION

The batching of a concrete mix load typically involves introducingcement, aggregates, water, and optional chemical admixtures into therotatable mixer drums of a ready mix truck wherein the components aremixed uniformly together and transported to a job site, where theconcrete mix is placed.

The terms “place” or “pour” may be used hereinafter to refer to variousmeans of conveying plastic concrete from the truck drum to its finalresting position at a job site. This includes expelling the concretefrom the drum onto a chute from where the concrete can flow or be pushedinto a space or formwork for slab, roadway, foundation, wall, or otherapplication; pumping concrete to a location in a high rise buildingabove ground level; spraying the concrete onto a surface, such as afoundation, wall, or tunnel surface; or depositing one concrete massonto a previously deposited concrete mass, such as in 3D printingprocesses.

If the concrete is to be used for making a horizontal slab, floor, deck,pavement, or road way, for example, the concrete will have a relativelynarrow time period or window within which the concrete can be“finished.” Finishing involves various steps, such as the leveling andsmoothing of the surface (troweling) to ensure its durability. Theforeperson (or manager) at the building site will want a sense of“initial set time,” or, in other words, will want to predict the momentwhen the poured concrete first develops strength such that it isworkable (i.e., the ability to be smoothened or moved into place) andthe surface finishing process can be begin. The foreperson will alsowant to have a sense of the “final set time” or the moment after whichthe concrete loses workability and can no longer be finished. This isparticularly the case when the foreperson does not have a constructioncrew for each concrete load poured, and limited resources must bemarshalled within short time spans.

Determination as to whether poured concrete can be finished (smoothed)is often done by judging the “water sheen” on the concrete surface, butthis test is subjective and often distorted by the need to finishquickly. Dusting issues, flaky surface defects, and large scale crackingmake it difficult to determine when a concrete surface is ready forfinishing. The usual “foot print” test for determining initial or finalset time is subjective and prone to error.

If the concrete is be used in a vertical application, such as a wall,column, or supporting structure (e.g., high rise buildings), theconcerns of the foreperson could focus on different aspects of set time.Understanding when the concrete begins to develop internal cohesion,leading eventually to increased stiffness and eventually hardness, willhelp applicators to understand better the proper rate at which theconcrete can be pumped or poured to avoid bursting the formwork.Understanding when the concrete begins to acquire compressive strengthcan enable the foreperson to determine how soon formwork can be removed;or to determine how soon the next concrete section can be cast on top ofa previously poured concrete section. Thus, the foreperson might like tounderstand better the nature of early set time as well as later set time(e.g., compressive strength of concrete at 1, 3, 7, or 28 days afterbatching).

The present invention focuses upon the determination of one or more settime values or value ranges, such as initial set time, final set time,and/or two or more set time values. This can involve the beginningand/or end of the workability/finishability window for plastic(workable) concrete; this can also involve strength values for hardened(non-workable) concrete such as compressive strength at 4 hours or at 1,3, 7, or 28 days, or at other ages.

Contractors at the building site might want to consider one set timevalue, such as final set time (by which concrete must be finished beforehardening); or they might want to consider a set time value range thatincludes, as another example, both initial set time (after whichfinishing can begin) and final set time (before which finishing must becompleted).

In FIG. 1, the present inventors illustrate a common problem using threeexample time lines representing three delivery trucks (designated as at10, 12, and 14) that carry concrete loads in mixer drums. Each load hasa different hydration behavior. Each load has a batch time (B) whichbegins at a batch plant and a different pour time (P) when the load isdischarged at the job site. As illustrated by the dotted line rectangle,the problem is caused by different set time values that define differenttime spans or ranges: e.g., different finishing start times (designatedat Fs) and different finishing completion times (designated at Fc). Asshown in FIG. 1, concrete poured from trucks 10 and 14 have similar pour(P) times. The finishing crew would be able to finish one poured load 10before working on poured load 14, as Fc for load 10 ends before Fs forload 14 begins. However, load 12 has a later pour time and a finishingstart time (Fs) that occurs later compared to the start time for load14. Load 12 also has a finishing completion time (Fc) that occursearlier compared to the finishing time for load 14. Thus,non-coordinated set time behaviors of the concrete pours greatlycomplicates the finishing process at the job site.

The concrete industry attempts to organize concrete deliveries bybatch-loading the trucks at set intervals (e.g., every 15 minutes), butthe underlying assumption that the trucks will arrive at similarlyspaced intervals at the job site is often challenged. For example, intraveling from the batch plant (B) to pour site (P), trucks can bedelayed by traffic and job site congestion, pump failures at the site,admixture dosing errors, temperature changes that affect hydration ofconcrete at the job site, and other problems. Inconsistency in concretemixes, such as different batch weights and mix designs (e.g., the loadmight contain returned concrete) can affect hydration behavior and giverise to set time value variations (e.g., Fs, Fc).

The result of uncontrolled set time values or value ranges in deliveredconcrete creates expensive and labor-consuming problems, such asconcrete sections that must be removed and replaced because they werenot finished within the applicable time.

SUMMARY OF THE INVENTION

In surmounting the problems mentioned above, the present inventionprovides a method for delivering concrete which involves adjusting oneor more assigned set time values or value ranges of the concrete mixload being delivered to a job site, preferably based on an assessment ofconcrete that was previously delivered to and placed at the job site,and to allow delivered concrete to have coordinated set time values orvalue ranges. This, in turn, allows for control over the properties inthe concrete.

As shown in FIG. 2, three concrete loads (B) are delivered in trucks(16, 18, 20) to a job site where they are placed (P) in accordance withan example embodiment of the present invention. In this example, therheology and hydration rate behavior of the concrete mixes are monitoredand adjusted such that post-placement set time value ranges do notoverlap. While it is possible to have some overlap (as part of thefinishing crew can begin to move from one section of poured concrete towork on the next section), for purposes of simplifying this illustrationthe finishing start times (Fs) and finishing completion times (Fc) forthe three poured concrete loads 16/18/20 are shown as non-overlapping.For example, if one had only a minimal number of crew workers on hand tofinish the placed concrete, the Fs and Fc time events could besufficiently spaced apart so that the crew could finish each pouredsection (e.g., 16 or 18) before proceeding to the next poured section(e.g., 18 or 20). It is also possible that the set time value rangescould overlap slightly, such as when the foreperson might have some ofthe finishing crew members move from one poured concrete section toanother while completing the necessary finishing before hardening; butthe objective is to avoid a number of concrete loads having coincidingset times (e.g., FIG. 1 at 12/14) where one does not have sufficientnumber of workers to complete the finishing stages.

Hence, the concept of the coordinating set time values or value rangesfor the present invention begins with the use of automated concreterheology (e.g., slump) management system on individual concreteready-mix delivery trucks, wherein the system is controlled by aprocessor that that allows for a set time value (e.g., initial set time)or value range (e.g., initial and final set time values, and/or strengthlevel) to be inputted into or calculated (e.g., by processor of slumpmonitoring system on board a concrete delivery truck).

The invention also allows for adjustment of the initial set time basedon concrete rheology data, such as by the foreperson at the site, orsuch as based on information from other concrete delivery trucks whichare monitoring various concrete loads delivered to the job site, orperhaps even based on sensor data obtained from sensors positioned aboveor on the surface of the placed concrete or embedded within the placedconcrete (or a combination of these).

For purposes of the present invention, the concept “set time value orvalue ranges” may refer to any number of activities, including: (a)initiation of finishing; (b) completion of finishing; (c) removingformwork or mold from concrete (i.e., after it hardens); (d) allowingfoot or car traffic upon the concrete; (e) casting further concrete ontop of the poured concrete; or other pour site activities, such as (f)pre-stress concrete mechanism adjustments. The set time value will bepresumed to start from the moment that the concrete load has been loadedor mixed at the batch plant, or otherwise readjusted (if it is returnedfrom a different job site or even from a different pour location at thesame job site) to reflect the moment that fresh concrete is batched ontop of the returned concrete load. In other words, the set time value orvalue ranges can cover any of a number time of placement time events oreven post-placement properties, such as concrete compressive strength atvarious ages, depending upon application.

Thus, an exemplary method of the present invention for coordinatingdelivery of concrete, comprises:

(A) providing at least two delivery trucks, each having a mixer drumcontaining a concrete load and a processor-controlled system formonitoring rheology (e.g., slump, slump flow, yield stress) and at leastone set time value or value range (e.g., initial set time, final settime, compressive strength, or mixtures of these values) of the concreteload in the drum, the processors programmed to perform functionscomprising:

-   -   (i) accessing at least one stored set time value or value range        assigned to concrete loaded in the mixer drum for delivery to a        job site;    -   (ii) calculating at least one current set time value or value        range for the load based on monitored hydration over time; and    -   (iii) comparing the at least one stored set time values or value        ranges with the calculated at least one current set time values        or value ranges; and

(B) adjusting current set time value(s) or value range(s) by introducinga set accelerator, set retarder, or mixture thereof into at least one ofthe at least two delivery truck concrete loads to effectuate or tomodify the sequential placement, finishing, demolding, formwork removal,or compressive strength phases of the concrete loads poured from the atleast two delivery trucks.

In further exemplary embodiments, stored or current set time valuescould include initial set time (after which finishing may begin), finalset time (before which finishing should be completed); and perhaps evena set time value range (e.g., defined by both initial and final settimes); and it could also include other placement events (e.g., thedevelopment of strength of poured concrete at one or more concrete ages,e.g., at 4 hours, 4 days, or other ages from time of batching). Again,there can be some overlap in terms of workability windows (e.g., the endtime for a prior pour might occur after the start time for subsequentpour). Set time values whether stored or current can be established, forexample, by monitoring of temperature changes in the concrete over time,preferably at given concrete slumps, using commercially available slumpmonitoring systems onboard the delivery truck. The present inventorsenvision that adjustment of current set time value or value range forthe concrete loads may be accomplished by administering doses of setaccelerator, set retarder, or mixtures thereof, using such commerciallyavailable monitoring systems (e.g., VERIFI® Monitoring Systems from GCPApplied Technologies Inc. of Cambridge, Mass.). Moreover, in furtherexample embodiments, the first job site might not be the eventual “poursite,” as the present invention facilitates re-routing of full orpartial delivery truck loads from a first job site to another job siteto deliver a full or partial load.

In further example embodiments, the monitoring of hydration of eachconcrete load over time can be done a number of ways. For example, thetemperature of the concrete load can be measured over time and takeninto consideration along with the batch amount (including load size atthe batch plant and any additional water or admixture added at any time,and additionally including the age of the concrete).

The present invention also provides a method for monitoring set timeconditions of a plurality of concrete placements, which comprises:

moving over a plurality of concrete placement locations at a job site atleast one aerial drone having at least one sensor for monitoringhydration over time of the placed concrete (e.g., sensors chosen fromoptical, infrared, acoustic, radio wave, microwave, electricalresistivity, electrical capacitance, and ultrasonic sensors) to obtaindata signals indicative of hydration;

comparing the obtained data signals with previously stored data signalsto obtain set time values or value ranges correlated with the hydrationover time data obtained from the at least one sensor; and

generating a pictorial diagram or map of the plurality of concreteplacement locations along with set time values or value ranges, orsuggested sequence priorities based on set time values or value ranges,thereby to provide indication of placements that are amenable tosequential treatment with respect to (a) initiation of finishing; (b)completion of finishing; (c) removing formwork or mold from theconcrete; (d) allowing foot traffic or car traffic on the concrete; (e)releasing tensioned cables from jacks (e.g., such as used inpre-stressed concrete applications); (f) anchoring or groutingpost-tensioned cables (e.g., such as for post-tensioned concrete); or(g) casting further concrete on top of previously poured concrete.

Further advantages and features of the invention are described infurther detail hereinafter.

BRIEF DESCRIPTION OF DRAWINGS

An appreciation of the benefits and features of the invention may bemore readily comprehended when the following written description ofpreferred embodiments is considered in conjunction with the drawings,wherein

FIG. 1 is an illustration of an example timeline of three ready-mixdelivery trucks having concrete loads wherein hydration states are notcoordinated, as explained in the Background Section above;

FIG. 2 is an illustration of an example timeline for ready-mix deliverytrucks having concrete loads wherein hydration states are coordinatedusing exemplary methods of the present invention, as explained in theSummary Section above;

FIG. 3 is a block diagram describing use of a UAV (aerial drone havingsensor) to monitor concrete setting status at a job site in accordancewith certain embodiments of the present invention;

FIG. 4 is a graphic illustration depicting a slab that is measured intwo pour locations, marked by the moisture content (i.e. MA and MB), ata specific time, t=20 min, in accordance with certain embodiments of thepresent invention.

FIG. 5 is a plot of normalized moisture values that are measured foreach section, A and B, over time, where the markers “0” and “X”represent measurements by an UAV, the solid line represents a fitlogistics curve, the dotted line represents a future prediction, and theshaded areas note windows of optimal finishing, in accordance withcertain embodiments; and

FIG. 6 is a plot of normalized moisture values including the secondderivatives, which show that local extrema can be related to the windowsof optimal finishing, in accordance with certain embodiments.

FIG. 7a is a plot of hypothetical measurements collected using a UAV(drone with sensor) at time 10 minutes after a reference time point, inaccordance with certain embodiments;

FIG. 7b is another plot of hypothetical measurements collected via a UAVat time 30 minutes after a reference time point, in accordance withcertain embodiments;

FIG. 7c is another plot of hypothetical measurements collected via a UAVat time 60 minutes after a reference time point, in accordance withcertain embodiments;

FIG. 7d is another plot of hypothetical measurements collected via a UAVat time 80 minutes after a reference time point, in accordance withcertain embodiments;

FIG. 8 is a plot of sensor data for two concrete placement regions overtime, along with a predictive model fit to each set of data;

FIG. 9 is a diagrammatic illustration of concrete delivery truck routesin accordance with certain embodiments;

FIG. 10 is a plot of experimental results for various opticalmeasurements of the surface of a poured concrete slab over time, inaccordance with certain embodiments;

FIG. 11 is a graphic illustration of the median intensity of the colorof a poured concrete segment (in terms of gray scale) over time whichcan be correlated with the setting characteristics of the concrete, inaccordance with certain embodiments;

FIG. 12 is a graphic illustration of gray-level contrast over time of acertain segment of a poured concrete slab which can be used to suggestset time value or characteristic, in accordance with certainembodiments;

FIG. 13 is a graphic illustration of the response of an infrared (IR)sensor to wavelength of 760-1100 nm being reflected by a poured concretesegment over time, in accordance with certain embodiments;

FIG. 14 is a graphic illustration of actual set time values (plottedalong horizontal axis) compared to predicted set time values (plottedalong vertical axis) as derived from a database of performanceattributes of concrete and physical properties of the concrete such asmix design, batched weight, or water/cement ratios;

FIG. 15 is a graphic illustration of actual set time values (plottedalong horizontal axis) compared to predicted set time values (plottedalong vertical axis) as derived from another database of performanceattributes of concrete and physical properties of the concrete such asmix design, batched weight, or water/cement ratios.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

As used in the specification, various devices and parts may be describedas “comprising” other components. The terms “comprise(s),” “include(s),”“having,” “has,” “can,” “contain(s),” and variants thereof, as usedherein, are intended to be open-ended transitional phrases, terms, orwords that do not preclude the possibility of additional components.

The term “concrete” typically refers to a mixture of cement (which oftencontains supplementary cementitious materials such as limestone, flyash, granulated blast furnace slag and other pozzolanic materials) andaggregates (e.g., fine aggregate such as sand, coarse aggregate such asgravel) and optionally one or more chemical admixtures (e.g.,plasticizers for increasing workability, set accelerators, setretarders, air entrainers, air detrainers, plastic shrinkage reducingadmixtures, corrosion inhibitors (for rebar) for modifying concrete inits plastic or hardened state. Concrete is considered to be hydratablematerial in that the addition of water into the mixture of cement andaggregates initiates a hardening reaction.

The term “cement” includes hydratable cement such as Portland cementwhich is produced by pulverizing clinker consisting of hydraulic calciumsilicates, aluminates and aluminoferrites, and one or more forms ofcalcium sulfate (e.g., gypsum) as an interground additive. Typically,Portland cement is combined with one or more supplemental cementitiousmaterials, such as fly ash, granulated blast furnace slag, limestone,natural pozzolans, or mixtures thereof, and provided as a blend, all ofwhich binds aggregates together to make concrete. Thus, “cement” and“cement binder” may also include supplemental cementitious materialswhich have been inter-ground with Portland cement during manufacture.

The term “concrete delivery truck(s),” also known as ready-mix concretetruck(s), shall mean and refer to a vehicle having a rotatable mixerdrum with non-vertical axis of rotation. Such mixer drums typically haveat least one blade or fin mounted on the inner wall of the drum andarranged spirally around the axis of rotation, such that rotation of thedrum in one direction forces concrete components towards a closed end ofthe drum (thus, in a mixing or loading mode); while rotation in theopposite direction expels materials through the open end of the drum(thus, in a pouring or expelling mode).

The phrase “batch time” or “batching time” is designated as “B” in FIGS.1 and 2 and is used to refer to various events, including, for example:(a) the time at which the truck begins to receive concrete or certainmix components for making concrete (e.g., cement, aggregates, water,optional chemical admixtures) into the mixer drum; (b) the time at whichone or more chemical admixtures (e.g., superplasticizer, set retarder,set accelerator, or mixtures thereof) are added into the mixer drumcontaining concrete or concrete components; (c) the time at which thematerials have been mixed together in the mixer drum and determined tobe uniformly mixed (e.g., such as may be determined by confirming thatslump sensor readings are relatively constant over a predefined numberof drum rotations); or (d) the time at which the truck leaves the batchplant.

For example, a particular batch plant might customarily indicate thetime at which components were introduced into the mixer drum, and thiscould be documented or memorialized in the electronic or paper batchticket; and, if an electronic batch ticketing is issued, the time couldbe transmitted to a dispatch center and/or the automated slumpmonitoring system of the delivery truck into which the concrete wasloaded, and this could be used to determine set time value or valueranges for the particular load.

The term “pour” means or refers to when a full or partial load ofconcrete is poured, sprayed, or otherwise deposited into final restingposition at the job site. Multiple pours can occur. For example, aninitial pour may be done to check the concrete properties. Adjustmentscan be made to the concrete which can continue to be poured. Partialpours may occur if the receptacle for receiving the concrete is full,or, if after checking the concrete properties, the load is to berejected. In these cases, the concrete may be returned to a batch plant,or to another location on the same or different job site, so that theremaining concrete can be used.

For purposes of FIGS. 1 and 2, the “pour” is designated as “P” andrefers to the moment when a full or partial load of concrete expelledfrom a delivery truck at a job site. One truck can have multiple pours.For example, an initial pour may be done to check the concreteproperties, and to permit adjustments to be made to the concrete, sothat remaining portions of a given load can be expelled from the truckinto position.

Partial pours may also occur if the formwork, mold, or pump hopper forreceiving the concrete mix is full. As another example, partial pourscan occur if the particular load is rejected; and the rejected concretemay be returned to a batch plant or to another location on the same ordifferent job site where the remaining concrete is put to use.

The meaning of the concept “set time value or value ranges” as usedherein and above will depend upon the particular application for a givenconcrete load. The concept may encompass only a single moment in time(e.g., final set) or it can comprehend a time period (e.g., both initialset and final set) as calculated from batching (or reconditioning ofreturned concrete). Thus, exemplary time set values or value ranges mayinclude the moment or period in time for any one or more of thefollowing activities: (a) initiation of finishing; (b) completion offinishing; (c) removal of formwork from or demolding of concrete; (d)allowing foot or car traffic upon the concrete; (e) releasing tensionedcables from jacks (as used in pre-stressed concrete applications); (f)anchoring or grouting of post-tensioned cables (as for post-tensionedconcrete); or (g) casting further concrete on top of previously pouredconcrete.

As explained above, for horizontal applications (such as pouring aconcrete highway, slab, floor, etc.), the set time values of likelyinterest would include “initial set time,” or, in other words, theearliest time (after batching or reconditioning of the concrete) atwhich pushing, leveling, screeding, smoothing, or texturing of theconcrete surface by trowel or other finishing tool can begin (See e.g.,ACI 302.1R-15). When the concrete becomes too stiff for finishing, thisis sometimes referred to as “final set time,” a term which can also beused to refer to the point in time after which formwork or mold can beremoved. See e.g., ASTM C191-18a, ASTM C266-18, ASTM C807-18, and ASTMC403-16.

Other set time values or value range might include, as another example,the initial set time and/or final set time, with a post-pour concreteproperty such as compressive strength. In some highway slab projects, ithas been desired to achieve a certain compressive strength target (400psi) within a given period of time (e.g., 4 hours). Again, the set timevalue or value ranges that one might desire to monitor and to adjust inthe concrete load will depend upon the specific application in which theconcrete load will be used.

As another example, for pre-stressed concrete applications, in whichsteel wires, cables, or rods are used for pre-stressing the concrete,the set time value or value range can include the earliest time (frombatching) for anchoring or grouting the cables in the concrete, and/orfor releasing tensioned cables from jacks.

The term “assigning” or “inputting” as used herein will refer to the settime value or value range that is entered into a processor formonitoring and/or adjusting the concrete load, and this could include,for example, the processor-controlled concrete monitoring system thatmonitors rheology (e.g., slump or slump flow) of the concrete mix loadcontained in the delivery truck drum. As mentioned above, this set timevalue or value range can be derived from an electronic ticket providedby the concrete batch manufacturer (e.g., many batch plants simply use15-minute intervals as batching times, whereby the delivery truck drivesunder a feeder system that loads cement, sand/rocks, and water into themixer drum and optional chemical admixture(s). Alternatively, set timevalue(s) or value range(s) can be calculated by an onboard (truck)processor based on rheology (or slump or slump flow) or other factors bythe processor.

It is contemplated by the present inventors that the exemplary methodsand systems of the present invention can be carried out using automatedslump management (monitoring) systems that are commercialized by GCPApplied Technologies Inc. through its affiliate Verifi, LLC, both ofCambridge, Mass., USA. Such concrete monitoring systems enable one tomanage the slump or other rheological properties (e.g. slump flow, yieldstress, viscosity) during in-transit delivery of the concrete from batchplant to jobsite where the concrete is placed. The patent literaturedescribes various automated process-controlled concrete monitoringsystems. Such systems can be configured and/or programmed to monitorrheology and various other concrete properties, and to deliveradmixtures into the mix load. See e.g., U.S. Pat. Nos. 8,020,431;8,118,473; 8,311,678; 8,491,717; 8,727,604; 8,764,273; 8,989,905; aswell as U.S. Ser. No. 11/834,002 (Publ. No. US 2009/0037026 A1); U.S.Ser. No. 14/052,289 (Publ. No. 2012/0016523 A1); U.S. Ser. No.14/052,289 (Publ. No. 2014/0104066 A1); U.S. Ser. No. 14/052,310 (Publ.No. 2014/0104972); PCT/US2015/025054 (Publ. No. WO 2015/160610 A1); andPCT/US2014/065709 (Publ. No. WO2015073825 A1), incorporated by referenceheren.

It is further believed that other sensors, such as force sensors (whichemploy stress or strain gauges), can be used to monitor the slump ofconcrete in the truck mixer drum. See e.g., U.S. Pat. No. 8,848,061 andUS Publication No. 2015/0051737 A1 of Berman (Sensocrete Inc./GCPApplied Technologies), U.S. Pat. No. 9,199,391 of Denis Beaupre et al.(I.B.B. Rheologie Inc.), or US Publication No. 2009/0171595 and WO2007/060272 of Benegas.

While automated concrete monitoring systems are used customarily formonitoring “slump,” it will be understood that the present inventionincludes monitoring of other rheology parameters such as slump flow,yield stress, viscosity, and other rheological parameters. The specificterm “slump” is employed as a matter of convenience.

An assigned or inputted set time value or value range, as previouslydiscussed, can be revised by the use of automated concrete monitoringsystems based on data analyzed by the system processor. Such data caninclude data obtained from electronic sensors used at the job site, forexample, to obtain moisture, humidity, temperature, or other properties.Data can also be obtained from the concrete monitoring system used onanother (e.g., lead) truck previously delivering concrete at the samepour site, and such data could include slump, temperature, watercontent, mix or batch proportions, or other information stored orderived by the onboard monitoring system.

In various exemplary embodiments, the revision of assigned or inputtedset time values can be undertaken by the management system processorbased on sensor data obtained from sensors that are used for monitoringone or more properties of the concrete after it is placed (i.e., poured,cast, screed, leveled, smoothened, etc.) at the job site.

Sensors Positioned Above Or At Concrete Surface. The present inventorsenvision that one or more moveable or portable sensors may be used formonitoring the surface of concrete once it is poured into place. Forexample, one or more sensors can be used in “unmanned aerial vehicles”(UAV) or drones, as explained further in the following paragraphs, orcan be suspended on hand-held poles, or suspended using cables or pulleyassemblies that can be moved over a slab, patch, or other segment ofpoured concrete. As another example, one or more sensors can be used innozzles for spraying, injecting, or depositing concrete (e.g.,shotcrete, injecting concrete into mines, depositing concrete such as in3D printing processes). The type of sensors that can be used may bechosen from optical, infrared, acoustic, radio wave, microwave,electrical resistivity, electrical capacitance, and ultrasonic sensors,and other sensor types, all of which are types of sensors known formeasuring a property of concrete while in its plastic and/or hardenedstate.

Sensors on Drones. The phrase “unmanned aerial vehicle” (UAV), or drone,refers to devices that can be flown by remote control and that can carryone or more sensors for monitoring concrete placements at a job site anda wireless transmitter for sending data signals to a processor, such asa processor onboard the concrete delivery truck, that communicates withone or more processors in the cloud, on one or more other deliverytrucks, and/or on one or more portable devices, including smart phones,tablets, or other portable devices at the job site. For example, in U.S.Pat. No. 8,599,646, Parrot describes the use of drones having ultrasonictelemetry devices to measure distances and topography withoutinterference from neighboring drone signals. In U.S. Ser. No.13/998,871, Newman describes a data collection system to enable dronesto collect image data, process the data for anomalies, and pair theimages to physical locations. U.S. application Ser. No. 14/843,455(MetLife) describes the use of drones to collect sensor data, convertthe data into insurance related information and transmit the datainformation through wireless communication. There have also beenimprovements which can enable the use of drones in difficult areas. U.S.Pat. No. 8,874,283 describes methods to enable drones to be utilized inenclosed spaces and controlled with or without line of sight to thedrone, which can be advantageous at a construction site.

In the construction field, drones have found use primarily in enablingdigitization and visualization of construction sites (see, e.g. CN104536456A). They have been used to capture aerial images that can bepresented to contractors or other site planners (See e.g., TREMCOSkyBEAM™ Asset Mapping). In US 2017/0016874A1, it was disclosed thatdrones can harvest data signals from sensors embedded in concrete at aconstruction site.

Sensors Embedded Within Concrete. In exemplary embodiments of theinvention, embeddable sensors may be employed. These are placed into thematrix of the poured concrete, or tied onto rebar before the concrete ispoured into a mold or formwork, and transmit data corresponding to thehumidity, temperature, hardening, and other properties of placedconcrete, through wired or wireless means. For example, embedded sensorshave been used in concrete structures for structural monitoring, Seee.g. U.S. Pat. Nos. 4,943,930, 8,913,952); strength development, Seee.g. U.S. Pat. No. 7,551,085; humidity measurement, See e.g. US Publ.No. 2007/0116402; as well as other applications, including corrosiondetection, See e.g. US Publ. No. 2015/0048844. Sensors have even beenenvisioned to be placed inside plastic concrete contained in concretedelivery trucks, See e.g., US Publ. No. 2015/0212061, and are intendedfor monitoring properties such slump, temperature, and humidity amongothers. These sensors can remain in the concrete as it is poured andprovide, for example, temperature readings that can be used forprediction of strength evolution of a hardening concrete slab. A numberof commercially available sensors can be embedded in concrete andgenerate signals indicating or corresponding to the temperatures and/orhumidity state(s) of the concrete. These include Giatec of Canada(SMARTROCK™ and BLUEROCK2™ sensors), Concrete Sensors Co. of Cambridge,Mass. (NOVOCRETE™ sensors); MATOlog of Finland (e.g., CURE™ sensors);Wake Inc. of Grandville, Mich., (HARDTRACK™ sensors); Quadrel LLC ofPittsburgh, Pa. (vOrb™ sensors); Flir of Wilsonville, Oreg.(INTELLIROCK™ sensors); and AOMS of Canada (LUMICON™ sensors).

Many of the above-mentioned sensors measure humidity through electricalresistivity or capacitance measurements and include a thermocoupleand/or piezo electric sensor for measuring temperature, and theytransmit data signals wirelessly to handheld devices, remote processors,and/or the cloud for real time monitoring and logging of temperature,humidity, and other maturity data. The signal data of sensors such asthese can be correlated with one or more physical properties (e.g.,compressive strength at various times after batching) and used by systemprocessor of slump monitoring system to adjust a current concrete load,such as by introducing one or more set accelerator, set retarder, ormixture of both, into the concrete.

Some of the sensors mentioned in the foregoing section which can beembedded in concrete may also be used when positioned against ordisposed upon the surface of the concrete. For example, one or moresensors can be fastened to formwork or molds against or into which theconcrete is cast; or tied or fastened to rebar, cladding, tunnel wall,foundation, or other structure against which concrete is cast orsprayed.

Various exemplary embodiments of the invention, with some furtherexemplary aspects for these various embodiments, are set forth below.

In a first example embodiment, the invention provides a method forcoordinating delivery of concrete, comprising:

(A) providing at least two delivery trucks, each having a mixer drumcontaining a concrete load and a processor-controlled system formonitoring rheology (e.g., slump, slump flow, yield stress) and at leastone set time value or value range (e.g., initial set time, final settime, compressive strength, or a combination of these or other values)of the concrete load in the drum, the processors programmed to performfunctions comprising:

-   -   i. accessing at least one stored set time value or value range        assigned to concrete loaded in the mixer drum for delivery to a        job site;    -   ii. calculating at least one current set time value or value        range for the concrete load based on monitored hydration over        time; and    -   iii. comparing the at least one stored set time values or value        ranges with the calculated at least one current set time values        or value ranges; and

(B) adjusting current set time value(s) or value range(s) by introducinga set accelerator, set retarder, or mixture thereof into at least one ofthe at least two delivery truck concrete loads to effectuate or tomodify the sequential placement, finishing, demolding, formwork removal,or compressive strength phases of the concrete loads poured from the atleast two delivery trucks.

In a first aspect of this first example embodiment, the system formonitoring rheology (e.g., slump) can be based on the use of one or morehydraulic pressure sensors (See e.g., U.S. Pat. No. 8,818,561 regardingsensors on both charge pressure port and discharge pressure port), forcesensors (e.g., strain or stress gauge), acoustic sensors, or acombination of these. Various known rheology monitoring systems werepreviously described above. Particularly preferred monitoring systemsare based on hydraulic pressure sensor(s) in combination with drumrotation speed monitors (e.g., gyroscopes, accelerometers on drum, orboth). Set time value or value ranges, whether stored or current, can begenerated for example through monitoring of temperature change over timeof the concrete load, preferably at given concrete slumps, using anautomated slump monitoring system. The monitoring of concrete load overtime can be done a number of ways. For example, the temperature of theconcrete load can be measured over time and taken into considerationalong with the batch amount (including load size at the batch plant andany additional water or admixture added at any time, and additionallyincluding the age of the concrete). The concrete loads after pouring atthe job site have set time values or value ranges which preferably donot coincide although there could be some overlap. In other exemplaryaspects, the first job site might not be the eventual “pour site” wherea truck is re-routed to travel from a first job site to another job siteto deliver a full or partial load. Adjustment of current set time valueor value range for the concrete load may be accomplished, for example,by administering doses of set accelerator, set retarder, or mixturesthereof.

In second aspect of the first example embodiment, the phrase appearingabove in Section A(ii) involving “calculating at least one current settime value or value range for the concrete load based on monitoredhydration over time” can involve one of many known ways for tracking thehydration of the concrete of time, including, in addition to trackingtemperature changes or the rate of temperature changes, the watercontent, slump change, or other known means of tracking hydrationstates. It is preferable for such tracking to include informationregarding the amount of cementitious material originally batched alongwith the concrete components in the mixer drum, and this can be obtainedfrom the ticket issued by the batch plant.

In a third aspect of the first example embodiment, at least two of theat least two concrete delivery trucks are bearing concrete loadsoriginating from different batch plants.

In a second example embodiment, which can be based on the first exampleembodiment described above, the invention provides a method wherein, instep (A), at least three delivery trucks (and more preferably at leastsix trucks) are provided, each having a mixer drum containing a concreteload and a processor-controlled system for monitoring rheology and settime value or value range of the concrete load in the drum, theprocessors programmed to perform functions (i), (ii), and (iii) aspreviously described; and each of the at least three delivery trucks(and more preferably at least six trucks) adjust the stored set timevalue or value range or the current set time value or value range of theconcrete loads.

In a third example embodiment, which can be based on the first or secondexample embodiment above, the invention provides a method wherein boththe stored set time value or value range and the current set time valueor value range are adjusted.

In a fourth example embodiment, which can be based on any of the firstthrough third example embodiments above, the invention provides a methodwherein the stored set time value or value range is calculated based onfactors which include the estimated age of the concrete at pour time.The estimated age may be calculated based, for example, on traffic, jobsite conditions, or other factors.

In a fifth example embodiment, which can be based on any of the firstthrough fourth example embodiments above, the invention provides amethod wherein set time values or value ranges are chosen from timevalues for (a) initiation of finishing; (b) completion of finishing; (c)removing formwork or mold from the concrete; (d) allowing foot trafficor car traffic on the concrete; (e) releasing tensioned cables fromjacks (as used in pre-stressed concrete applications); (f) anchoring orgrouting post-tensioned cables (as for post-tensioned concrete); or (g)casting further concrete on top of previously poured concrete.

In a sixth example embodiment, which can be based on any of the firstthrough fifth example embodiments above, the invention provides a methodwherein the stored set time value or value range accessed by, oraccessed and adjusted by, at least one of the delivery truckprocessor-controlled systems is derived from (a) ticket informationprovided by a batch plant which sourced the concrete in the truck mixerdrum (e.g., the ticket information may include mix design, materialbatch weights, concrete load volume, water content or water/cementratio, or combination thereof); (b) foreperson at job site whereconcrete from the truck mixer drum is to be poured (e.g., the forepersoncould take into consideration job-site conditions including but notlimited to ambient temperature, relative humidity, wind speed, UV index,traffic congestion, worker conditions, etc.); (c) a processor thatreceives data signals from humidity, moisture, and/or temperaturesensors embedded within, positioned against the surface of, or embeddedwithin concrete poured or placed at the job site or another job site (ora combination of such sensors); or (d) a processor monitoring of anotherconcrete delivery truck having a processor-controlled system formonitoring rheology and set time value or value range of the concreteload (e.g., the lead delivery truck or other delivery truck pouringconcrete at the job site having an earlier set time value or valuerange).

In a first aspect of the sixth example embodiment, a humidity, moisture,and/or temperature sensor can embedded within and/or placed on thesurface of the poured concrete.

In a second aspect of the sixth example embodiment, one or more sensorscan be suspended above poured concrete at the job site using aerialdrones, cables, poles, or other suspension means. Preferred sensors forthis application may be chosen from optical, infrared, acoustic, radiowave, microwave, electrical resistivity, electrical capacitance, andultrasonic sensors, or combinations thereof. These sensors can providedata signals indicative of hydration state or rate of the concrete, andsuch data signals can be transmitted, preferably wirelessly, so that thesystem processor on board the delivery truck can monitor the currenthydration state of the concrete load, and can record and store theinformation so that it can be used later as historical (stored)information and correlated with a target set time value or value range.

In a third aspect of the sixth example embodiment, sensors (e.g.,conductivity, ultrasonic) can be used inside hoses for injecting ordepositing concrete at the job site, such as in nozzle or hoses used forspray-application of shotcrete, nozzles for depositing concrete in a 3Dprinting process, or for expelling concrete sections such as for makingtunnels or precast concrete shapes.

In a seventh example embodiment, which can be based on any of the firstthrough sixth example embodiments above, the invention provides a methodfurther comprising adjusting the at least one stored set time value orvalue range, and providing a report or indication of adjustments made tothe at least one stored set time value or value range. In a first aspectof this example, the monitoring system of the delivery truck will use atleast one stored set time value or value range, e.g., initial set time,final set time, time for removing formwork from the concrete, and willbe able to adjust the store values or value ranges based on new datainformation, such as obtained as described in the sixth exampleembodiment above. Thus, the foreperson at the job site where theconcrete is to be poured (or sprayed or otherwise placed) can sendinstructions to the processor to add 5 or 10 minutes to the set time dueto a delay at the job site. As another example, a remote processor oreven the processor used for monitoring a delivery truck concrete loadcan receive data signals or other information derived from sensorsembedded in or positioned above or against concrete that was previouslypoured, and make adjustments to the stored set time values so that thetruck system processor can used the revised values to make adjustmentsto the current set time value of the concrete load in the truck. Infurther examples, the system will enable a record or confirmation of theadjustments made to the stored set time value or value range.

In a second aspect of this example embodiment, adjustments to the storedset time value can be sent to or retrieved by the concrete monitoringsystems on other concrete delivery trucks and used for coordination ofpouring and finishing events at the pour site.

In an eighth example embodiment, which can be based on any of the firstthrough seventh example embodiments above, the invention provides amethod wherein the current set time value or value range is compared tostored set time value or value range in terms of at least one factorchosen from temperature of concrete, rate of temperature change in theconcrete, batch amounts or mix design of the concrete, adjustments inwater or admixture (e.g., cement dispersant, chemical plasticizing orsuperplasticizing admixture) added into the concrete load, rheology(e.g., slump, slump flow, yield stress), or other property of theconcrete

In a ninth example embodiment, which can be based on any of the firstthrough eighth example embodiments above, the invention provides amethod wherein at least one of the concrete loads in one of the at leasttwo delivery trucks is returned concrete (e.g., returned from the sameor different job site, optionally but likely to contain set retarderadmixture that was administered into the partial remaining load in themixer drum), and further wherein the comparison of stored and currentset time values or value ranges includes consideration of the age ofconcrete from the initial batching of the concrete which was returnedfrom the job site.

In a tenth example embodiment, which can be based on any of the firstthrough ninth example embodiments above, the invention provides a methodwherein a first concrete load from a first delivery truck is poured intoplace, and a second concrete load from a second delivery truck is pouredon top of the first concrete load while the first concrete load is in aplastic state, and wherein the first load and second load haveoverlapping set time values or value ranges.

For example, in U.S. Pat. No. 7,968,178, Scurto et al. disclosed that afirst slab of concrete could be cast onto a first concrete slab while itwas still in a somewhat plastic state, so as to create an integratedregion between the successively cast slabs. In this manner, the presentinvention can permit set time values or set time value ranges, asbetween successive or nearby concrete load deliveries at a job site, tobe slightly overlapping, so as to facilitate bonding between concretethat is poured, sprayed, printed, deposited, or otherwise placed ontoprevious concrete that is still in a plastic state. In the constructionindustry, one may hear a contractor speak about casting a “first lift”(e.g., first concrete mass or structure), and then casting a “secondlift” on top of the first one. This is frequently related to the castingself-consolidating or self-compacting concrete. Although the concrete,due to its fluidity, can be cast quickly, the fluid concrete can imparta great force on formwork, increasing the risk of “blow-outs” where theformwork catastrophically fails. Based on coordinated set times, thefluid concrete can be left to stiffen, where the next “lift” can be castsafely upon it.

In an eleventh example embodiment, which can be based on any of thefirst through tenth example embodiments above, the invention provides amethod wherein the stored set time value or value range for concretepreviously delivered and placed at the job site is obtained or derivedfrom data signals generated by at least one sensor in the nozzle, hose,or other conduit of concrete during deposition or spraying of theconcrete through the nozzle, hose, or conduit at a job site. Forexample, the sensor could be an electrical conductivity sensor (or twoelectrodes spaced apart within the nozzle and/or hose so that a currentcan be sent through the electrodes and conductivity of the concrete canbe measured); or the sensor could be of the type of sensors (e.g.,infrared (IR), ultrasonic) previously mentioned above.

In a twelfth example embodiment, which can be based on any of the firstthrough eleventh example embodiments above, the invention provides amethod wherein a portion of the concrete load in at least one of thedelivery trucks is poured at a first job site, and, within fifteenminutes and more preferably within ten minutes of the pour, a dose ofset retarding agent is introduced into the remaining portion of theconcrete load in the delivery truck, and the remaining portion istransported by the delivery truck to a second job site and poured intoplace at the second job site. In further aspects of this example, atleast one subsequent dose of set retarding agent is administered intothe remaining portion of the concrete load during transit from the firstjob site to the second job site.

In a thirteenth example embodiment, which can be based on any of thefirst through twelfth example embodiments above, the invention providesa method wherein at least five (and more preferably at least ten)delivery trucks are provided in accordance with step (A) having concreteloads whose set time values or value ranges are adjusted in accordancewith step (B), said adjustments being made using set time value or valuerange calculations based on signal data obtained or derived from atleast one sensor for monitoring hydration over time of placed concreteat the job site.

In a first aspect of this thirteen example embodiment, the hydrationover time signal data for a plurality of concrete placement locations ata job site is generated by at least one sensor chosen from optical,infrared, acoustic, radio wave, microwave, electrical resistivity,electrical capacitance, and ultrasonic sensors, and the at least onesensor is preferably moved over the concrete placement locations usingan aerial drone. A processor, such as the one used for monitoringrheology of the truck concrete load can be programed to compared theobtained data signals with previously stored data signals to obtain settime values or value ranges correlated with the hydration over time dataobtained from the at least one sensor; and, in further exemplaryembodiments, a processor, such as a personal computer, lap top, orhand-held smart phone or smart watch can be used to generate a pictorialdiagram or map of the plurality of concrete placement locations alongwith set time values or value ranges, or suggested sequence prioritiesbased on set time values or value ranges, thereby to provide indicationof placements that are amenable to sequential treatment with respect to(a) initiation of finishing; (b) completion of finishing; (c) removingformwork or mold from the concrete; (d) allowing foot traffic or cartraffic on the concrete; (e) releasing tensioned cables from jacks(e.g., such as used in pre-stressed concrete applications); (f)anchoring or grouting post-tensioned cables (e.g., such as forpost-tensioned concrete); or (g) casting further concrete on top ofpreviously poured concrete.

In a second aspect, the hydration state of various placed concretesections can be indicated on a visual monitor in terms of darkenedsection, or other visual aids, corresponding in darkness with state ofhydration.

In a fourteenth example embodiment, which can be based on any of thefirst through thirteenth example embodiments above, the inventionprovides a method for monitoring set time conditions of placed concreteloads, the method comprising:

moving over a plurality of concrete placement locations at a job site atleast one aerial drone having at least one sensor for monitoringhydration over time of the placed concrete (e.g., sensors chosen fromoptical, infrared, acoustic, radio wave, microwave, electricalresistivity, electrical capacitance, and ultrasonic sensors) to obtaindata signals indicative of hydration;

comparing the obtained data signals with previously stored data signalsto obtain set time values or value ranges correlated with the hydrationover time data obtained from the at least one sensor; and

generating a pictorial diagram or map of the plurality of concreteplacement locations along with set time values or value ranges, orsuggested sequence priorities based on set time values or value ranges,thereby to provide indication of placements that are amenable tosequential treatment with respect to (a) initiation of finishing; (b)completion of finishing; (c) removing formwork or mold from theconcrete; (d) allowing foot traffic or car traffic on the concrete; (e)releasing tensioned cables from jacks (e.g., such as used inpre-stressed concrete applications); (f) anchoring or groutingpost-tensioned cables (e.g., such as for post-tensioned concrete); or(g) casting further concrete on top of previously poured concrete.

In a first aspect of this fourteenth example embodiment, the pictorialdiagram or map can be generated on a hand-held device, or, as anotherexample, on goggles worn by a site foreperson. The pictorial diagrammay, for example, be a picture or image of concrete delivery trucks asviewed on a pour site map, and allow for digital values and/or colors tobe overlaid upon the truck images or concrete segment images. Thus, asite foreperson could direct delivery trucks to get into line forpouring, or to pour, according to visual information as to pour status(i.e., set time value); and/or could direct finishing crew to thosesegments of poured concrete which have necessary setting values orcharacteristics.

FIG. 3 is a block diagram which illustrates an exemplary process inaccordance with certain embodiments of the invention. First, concrete isdelivered to the placement site (block 22) and then poured, spread, andconsolidated (block 24). For each concrete delivery truck load (or groupof concrete delivery truck loads) of concrete thus placed, an UAV (orfleet of UAVs) can determine one or more perimeters of the placedconcrete using telemetry based on optical and thermal signals (block26). For example, the color difference (determined from comparingsequential images), or the heat signature from the concrete, candelineate the poured concrete from form edges or pre-placed concrete, asthe formwork and concrete typically have different temperatures.Alternatively, image analysis comparing before and after pouring canalso help determine a perimeter of the placed concrete. Using thisinformation, a processor-accessible database can be uploaded with, forexample, the identification of the concrete delivery truck (e.g.,concrete delivery truck number) that delivered the concrete, the batchticket (containing the concrete constituents or mix design, e.g. watercontent), the time the concrete was poured, and the location of theconcrete. This information can help determine if all sections of themold are properly filled, and if not, the contractor can be alerted tovibrate and add more concrete.

Also as shown in FIG. 3, the concrete article can be monitored fordifferent properties (blocks 30, 32, 35, 36 and 38). For example, theUAV can scan the poured concrete article for differences in density thatmight indicate consolidation issues to be addressed before the concretehardens. Available technologies that may be used by the UAV to carrythis out include nuclear density gauges, ground penetrating radar, orcapacitance energy dissipation (See, e.g. U.S. Pat. No. 5,952,561). Thepresent inventors also envision that air-coupled surface wavemeasurements can be employed in the present invention (See e.g., USPublication No. 2013/0289896). If differences in density are discovered(block 40), the affected areas can be relayed to the contractor by, forexample, a mobile application so that the contractor can visually seewhere consolidation needs to be addressed through further compaction orvibration. This can be accomplished for example by inserting vibratoryrods at specified locations and may even require additional concrete tobe added. Furthermore, augmented reality methods can also be utilized tomore easily view areas of issues (see, e.g., U.S. Pat. Nos. 8,922,590and 8,943,569, both incorporated herein by reference).

After placement and consolidation, the UAV (drone) can periodically scanthe topography of the concrete article using, for example, imagedevices, such as optical telemetry or terrestrial laser scanning todetermine areas of high and low spots that require refinishing. Duringthe screeding process and the initial floating process (which includesbull floating, straight-edging and darbying), the UAV can periodicallyscan the concrete article and determine properties such as surfacemoisture, which can be determined through optical telemetry (forexample, light reflectance, or comparing past images with the currentimage), through near infrared sensing, which is sensitive to water (Seee.g., U.S. Pat. No. 7,265,846, incorporated herein by reference),through radar (See e.g., U.S. Pat. No. 9,207,323, incorporated herein byreference), among other methods. Periodic scanning can includecontinuous scanning, or can include continual scanning such as, forexample, fly-bys every 5 minutes, or every 10 minutes, or howeverfrequent is deemed necessary based on how fast the concrete is settingor a change in the rate of setting. The path of the fly-by can also bevaried, based on, for example, the region of a concrete article that isbeing monitored, or simply unobstructed flight paths. When measurementsare collected over time and spatially over the concrete article,predictive mathematical models can be constructed such that the surfacemoisture can be predicted. Such models can be used to send to contractorat the building site useful information. Mobile applications oraugmented reality methods can be used on lap tops or smart phone devicesto indicate sections of poured concrete having, for example, surfacemoisture that will soon exceed a predetermined threshold, whereby thecontractor can determine when and where screeding and initial floatingmust be completed (See block 42 of FIG. 3). Any screeding and/or initialfloating outside of the applicable workability window will result industing or scaling of the concrete surface, and hence repair costs thatshould be avoided.

FIG. 4 illustrates a bird's eye view of a poured concrete slab. Thisbegins a discussion of how one can generate helpful mathematical modelsfor generating visual indications of set time behavior for poured slabs.Moisture measurements are taken in two poured sections A and B (shownside by side for sake of convenience). FIG. 5 illustrates the moistureof each slab section A and B (66 and 75%) at a specific time (t=20minutes). Measurement locations do not have to be aligned in a gridfashion, or taken consistently in the same location. For thisdiscussion, the location of the measurements over time will be heldconstant. Measurements are taken in each of the two locations (at A andB shown in FIG. 4) over time. As more data is gathered, the model can berefined in real time. In other words, for each new data point that iscollected, the model is rebuilt or refined to take into account the newdata. The predictive models aim to detect one or more features in datacurves that relate a monitored property (e.g. temperature, strength, settime or moisture) over time. A feature may be a local or global extrema(e.g. a peak or a valley), or an inflection point, or simply exceedingor falling below a pre-defined threshold. For this case, it is assumedthat the inflection point of the curve representing the moisture overtime represents the optimal time to finish the concrete. Again,finishing the concrete requires a minimum stiffness of the slab and amaximum moisture on the surface. Furthermore, as the concrete hardens,and more water leaves the surface, finishing becomes more difficult.Thus, optimal time exists.

In FIG. 5, the complete moisture evolution through the optimal time andbeyond is plotted for each section. The markers “0” and “X” representthe data collected, while the line represents a logistic function fitusing standard least-square methods. The shaded region indicates asuitable finishing window for sections A and B. This can be determinedthrough comparisons between historical data, for example, penetrationtests (see e.g. ASTM C403-16) that measure the finishing window directlyand compared to sensor data signals obtained over the same time period.As can be seen, the inflection point exists within the window. Thus, ifthe inflection point can be determined in real time, the contractor canbe alerted to start the finishing process.

In some cases, it may be more useful to alert the contractor at thestart of the finishability time window, instead of in the middle of thewindow. In this case, the second derivative can be calculated usingstandard calculus techniques on an assumed form of a function that isfit to the data (e.g., a logistics function, a quadratic function, alinear function, etc.). The second derivative with respect to time canalso be calculated numerically using finite differences. Using thelatter process, smoothing of the original data may be necessary,although an assumed function form (e.g. logistics function) does nothave to be assumed, which can be an advantage in some cases where theform of the function is difficult to determine a priori.

FIG. 6 is a graphic illustration of another exemplary embodiment whereinsecond derivative can be used to generate higher resolution of data tosuggest when finishing can be initiated or completed.

Additionally, further analysis can be carried out to predict time valueswhen finishing can start and end. Taking the third derivative withrespect to time can help to monitor how close the third derivative is tozero, which indicates the maximum or minimum in the second derivative.Based on how fast the third derivative is converging to zero, the timesat which the maximum and minimum occur (and thus the start and end ofthe finishing window), can be predicted and reported to the contractoror other jobsite personnel.

After initial floating operations are done, a slight stiffening mustoccur in the concrete before edging or jointing are performed; suchstiffening is described as “ . . . sustain[ing] [a] foot pressure withonly approximately ¼ in. (6 mm) indentation.” See e.g., ACI 302.1R-15.Alternatively, a drone-carried sensor can be used for periodicmonitoring of properties such as concrete stiffness through a pressuremeans (e.g., a force probe or penetrometer mounted on the drone);through ultrasonic transducer/receiver/transmitter unit for measuringshear acoustic waves or Rayleigh waves; or, as another example, throughelectrical resistivity or temperature sensors. Continual measurementover time and space (area of the concrete article such as a slab)enables a predictive mathematical model to be constructed such that thestiffening can be predicted similar to what was described previously.For example, monitoring the temperature for initial set can indicate thetime to finish the concrete article. By taking the second derivative ofthe temperature with respect to time (either using an assumed functionor via finite differences), a local maximum in the second derivative canindicate initial set. A similar approach can be taken with outputs fromother sensors as previously mentioned. This information can be presentedusing such mathematical models, so as to provide visual indications asto which parts of the poured concrete sections exhibit sufficient (e.g.,exceeds a predefined threshold). Using this information, the contractorcan direct finishers to begin power floating and troweling on specificsections of the concrete. The placed order of the concrete may notcorrespond to the sections requiring earlier attention, as the concretethat is placed, for example, in areas more exposed to sun or wind mayhave accelerated set time behaviors; or the inconsistency in thetruckloads of concrete (especially concerning water content) for example(see e.g., block 44 of FIG. 3) can also change set time behavior.

Once the power floating is complete, and during the troweling operation,the UAV can periodically scan the concrete article and determine surfacecolor and texture through optical telemetry or terrestrial laserscanning (block 46 of FIG. 3). Continual measurement over time and space(area of the article, e.g., area of a slab) enables a comparison betweenlocations so that locations that are out of specification (e.g. viacolor analysis) or have not been finished (e.g. via texture analysis)can be relayed to the contractor (again, for example, through a mobileapplication or augmented reality method) to indicate which areas that nolonger need to be troweled, and areas that still require finishing(block 50). This can prevent detrimental surface color and texturevariation.

While FIGS. 4-6 Illustrate the use of time and space models for a simplegrid consisting of two sections where measurements were collected in themiddle of the sections at regular intervals, FIGS. 7a-d demonstrate howa predictive model can be developed through use of data collected usingone or more sensors onboard an unmanned aerial vehicle (UAV), commonlyreferred to as a drone, in a more complex, but more generalized fashion.

In FIG. 7a , fifty hypothetical measurements have been collected by useof sensor on a drone, each measurement location noted by a circle with anumber next to it. It is not necessary that the measurements are made ina regular grid fashion. In each of 7 a-d, a Voronoi diagram was createdusing the fifty measurements. Each Voronoi “cell” is an area associatedwith each measurement. This is a standard method to partition an areainto regions based on a group of points within the area. In essence, foreach measurement, the area, or cell is defined as all areas closer tothat measurement than to any other measurement. FIG. 7a employs a shadeof grey for each region corresponding to a normalized value. Forexample, this could represent the moisture, temperature, or stiffness ofthe article, or even an acoustic measurement. FIG. 7a furtherillustrates the normalized value across the article ten minutes after areference time (e.g. when the concrete was placed or when the concretewas batched).

FIGS. 7b-d illustrate subsequent hypothetical set time value (hydrationstate) measurements using one or more sensors on a drone (UAV),positioned above various sections of poured concrete, at times of 30, 60and 80 minutes, respectively, after a reference time. The measurementsdo not necessarily have to be at the same locations as the previous timeperiod. If different locations are measured over time, preferablynumerous measurements should be taken to obtain a representativesampling. It is envisioned that similarly behaving regions of pouredconcrete can be grouped together (e.g., if a temperature differencebetween the two is below a pre-defined threshold). As time progresses,as shown in the exemplary embodiment illustrated in FIGS. 7a through 7d, the shaded regions become darker, but not all at the same rate. Inparticular, the lower right-hand corner does not become darker as fastas the rest of the article. This can simply be a result of this sectionbeing poured at a later time than the rest of the article, or a morecomplicated reason, such as the concrete mix is not the same (e.g. adifferent water content in a particular load). In any event, using thedata collected at each time period for each region (in this case, thelower right-hand corner region and the complementary region), arelationship or model over time can be developed.

FIG. 8 illustrates a hypothetical example of the model suggested above.Each marker represents the average sensor measurement or data signalvalue for a particular region at a given time period. At 60 minutes, thedata is used to fit a model to predict future behavior, which isrepresented by the dotted portion of each curve. The horizontaldash-dotted line can represent a threshold to trigger a finishing eventsuch as “Begin power floating.” This trigger point can be determined bycomparing the measurements to empirical data obtained from pastdeliveries. More preferably, a specific characteristic (or combinationof characteristics) can be correlated to the trigger point.

FIG. 8 also illustrates how a logistic function can be used for themodel. The trigger point can be correlated to an inflection point on alogistic data curve, for example the point at which the curve changesfrom concave to convex (or vice versa). Using this example, powerfloating of concrete sections indicated in the lower right region ofFIG. 7c can begin in about 20 minutes, while power floating for othersections can begin in approximately 3 minutes. This predictive tool canprevent serious surface damage from power floating activities that begin(for example) too early or too late.

Many different sensors can provide measurements over both time and spaceto yield information that can indicate when to start and completedifferent phases of the finishing process. Relationships can bedeveloped between physical phenomena such as changes in surface moistureor stiffness of the concrete article. Some of these relationships existin the literature, for example the relationship between penetrationtests and slab stiffness. Other relationships require more in-depthanalysis and additional parameters. For example, if using an opticalsensor, machine vision (see e.g., Machine Vision, R. Jain, R. Kasturi,B. Schunck) can be a useful mathematical tool to pick outcharacteristics over subsequent images that can relate to, for example,changes in surface moisture. Determination of color, shading and texturecharacteristics can be particularly useful. For example, the meanintensity, entropy, energy, contrast, homogeneity and correlationcalculations can be used to analyze subsequent images over time (seee.g. Machine Vision, R. Jain, R. Kasturi, B. Schunck, pp. 234-248).Different characteristics will be more or less sensitive to differentsituations (e.g. an indoor slab versus and outdoor slab).

Aside from improving finishing operations, drones have other uses. Forexample, the same method to collect data from the concrete article bothin a temporal and spatial manner, can be used to generate a mathematicalmodel for temperature, hydration (e.g. initial and final set), concretestrength (e.g. via a maturity method such as ASTM C1074-17), andmoisture changes over time. As each point or group of points arerecorded, the sensor measurement(s) can be fed into a processor suchthat the predictive model can be regenerated, or updated to include thenew data points. Thus, the predictive model adapts to new data and isnot just a static model. This prediction can further enable thecontractor to make logistic decisions at the jobsite.

Furthermore, set time predictions (initial and final set as well astimes to start surface finishing or times that the surface finishing canbe completed by) can be recorded along with all other data associatedwith the concrete including what concrete delivery truck loadscontributed to the section of concrete article, the batch weights foreach concrete delivery truck load, the slump of each concrete deliverytruck load, other rheological characteristics of the concrete deliverytruck load, the air content of the concrete delivery truck loads, totalwater and admixture dosages including those dosed during transit foreach concrete delivery truck load, etc. By collecting these data as theyare generated and recording the data in a database, additionalpredictive models can be generated which related the associated data fora given load (i.e. pre-pour data) to post-pour data including set time.Thus, for a given concrete delivery truck load being directed to aparticular job site, the set time can be predicted. This is illustratedthrough Example 4 described hereinafter.

Alternatively, set time estimations can be obtained by assuming aparticular load for the same job has a similar set time to a previousload given that the pre-pour conditions are similar (e.g. the totalwater content is within 5 pounds per cubic yard of concrete, or theslumps are within 1″, etc.). By using the predicted set times andcomparing to a target set time, a difference in set times can beestablished. Based on this difference, along with any extra timerequired, an appropriate dosage of set retarder can be calculated andadministered to adjust concrete set times, so that placement of concreteenroute or re-routed can be coordinated, as explained in the detailedexplications of hypothetical illustrations which follow.

FIG. 9 illustrates an example of two batch plants which each normallysupply two job sites. The present invention enables a partial orcomplete load, unused or rejected at one of the sites, to be sentdirectly or indirectly to the other site. The route 110 between Plant 1(P₁ at 102) and Jobsite A (J_(A) at 104) has a transport time of 45minutes (1 way). The route 114 between Plant 1 to Jobsite B (J_(B) at108) has a transport time of 25 minutes. The route between Plant 2 (P₂at 116) and J_(B) has a transport time of 10 minutes. The route 116between P₂ (106) and J_(A) (104) has a transport time of 6 minutes. Theroute 118 between the two jobsites J_(A) and J_(B) has a transport timeof 12 minutes.

With reference to FIG. 9, assuming for illustrative purposes that Plant1 (102) is dedicated to delivering to Jobsite A while Plant 2 (106) isdedicated to delivering to Jobsite B (108), the present inventionenables a scenario wherein concrete from Plant 1 to Jobsite A (104) isrejected at Jobsite A but can be delivered to Jobsite B (108). Toreceive a ticket authorizing this rerouting, or to make adjustments tothe mix (e.g. add cement), the concrete delivery truck must ordinarilytravel route 110 in both directions (i.e., it must return to Plant 1 at102) and then travel route 112 to Jobsite B at 108. The total timerequired by this travel distance is 45×2+25=115 minutes (not countingthe time for receiving the ticket and making any adjustments to theconcrete). Ordinarily, Jobsite B (108) receives concrete from Plant B(106) by way of route 114 which normally requires only 10 minutes. Thus,the rejected delivery from Plant 1 is 105 minutes older (115 minus10=105) as compared to typical deliveries from Plant 2 to Jobsite Bwhich travel along route 114. It is not surprising, then, that thefinishing time of the concrete from Plant 1 will be different comparedto the concrete from Plant 2. This leads to serious issues, as theconcrete from Plant A could set 105 minutes earlier as compared to theconcrete ordinarily delivered from Plant B (106) to Jobsite B (108).

With reference to FIG. 9, assuming for illustrative purposes of anotherexample, if we consider that concrete from Plant 2 (106) to Jobsite B(108) by route 114 is rejected for use at Jobsite B, then for purposesof re-use at Jobsite A, the delivery truck must ordinarily travel route114 twice (since it must ordinarily return to Plant 2 to obtain a ticketauthorizing delivery to Jobsite A) and then travel route 116 to JobsiteA. The total time (again, not including the time to receive a new ticketand adjust the mix design) will be 10×2+6=26 minutes. This is 19 minutesless than typical concrete deliveries from Plant 1 to Jobsite A.Concrete from Plant 2 arrives sooner to Job A and will set 19 minuteslater in time as compared to concrete from Plant 1.

In a further exemplary illustration based on FIG. 9, let us assume thatPlant 1 (102) is dedicated to delivering to Jobsite A (104), while Plant2 (106) is dedicated to delivering to Jobsite B (108). Also assume thata concrete load delivered from Plant 1 to Jobsite A is rejected, but canbe delivered to Jobsite B. In exemplary embodiments of the presentinvention, an electronic ticket can be issued as soon as the concretedelivery truck is confirmed to deliver to Jobsite B. This eliminates theneed to have the concrete delivery truck, situated at Jobsite A, returnto Plant 1. The delivery time from Plant 2 to Jobsite B can be sent tothe processor for the concrete management system that controls themonitoring of the concrete load on the concrete delivery truck. This canbe based on, for example, the time of the last delivery, an average ofseveral past deliveries, or a forward prediction of the next delivery.The processor also receives an estimate for the current concretedelivery truck to reach Jobsite B from Jobsite A, including time theconcrete has already traveled from Plant 1 to Jobsite A. In this case,the delivery time from Plant 2 to Jobsite B via route 114 is 10 minutes,and the delivery time from Plant 1 to Jobsite A and from Jobsite A toJobsite B will be a total of 57 minutes. Thus, the concrete originatingfrom Plant 1 will be 47 minutes older than concrete originating fromPlant 2. In this case, the processor calculates the amount of retarderrequired to retard the concrete by 47 minutes, and the retarder is dosedon the concrete delivery truck accordingly. The dosage may be carriedout manually or automatically.

FIG. 9 also allows one to consider a further scenario enabled by thepresent invention, where a concrete delivery from Plant 2 (106) toJobsite B (108) is rejected for use at Jobsite B, but could be used atJobsite A. In this case, once the delivery from Plant 2 to Jobsite Boccurs the concrete is needed for Jobsite A, an electronic ticket can beissued (e.g., to the processor-controlled management system onboard thedelivery truck), thus eliminating the need for the truck to return toPlant 2 and then to have to travel from Plant 2 to Jobsite A. Thedelivery time from Plant 1 to Jobsite A can be sent to or stored on thetruck, as well as an estimate for the current concrete delivery truck toreach Jobsite A including time already traveled. Thus, in this examplethe delivery time from Plant 1 to Jobsite A is 45 minutes and thedelivery time from Plant 2 to Jobsite B and from Jobsite B to Jobsite Atotals 22 minutes. Thus, the concrete originating from Plant 2 will havebeen batched 22 minutes after the batch time for the concrete which istypically delivered to Plant 2 from Plant 1. In this case, the processorcalculates the amount of accelerator needed to accelerate the concreteby 22 minutes, and the accelerator is dosed on the concrete deliverytruck. The accelerator may be dosed either manually or automatically.Alternatively, the concrete delivery truck driver or jobsite coordinatoris instructed to wait approximately 22 minutes before pouring theconcrete.

In a still further example of the advantages and features of the presentinvention, using FIG. 9 as an illustration, let us assume Plant 1 (102)is dedicated to delivering to Jobsite A (104) and Plant 2 (106) isdedicated to delivering to Jobsite B (108). Assume also that a concretedelivery truck that travels from Plant 1 to Jobsite A is rejected, butit can be delivered to Jobsite B. Additionally, the mix design of thecurrent concrete delivery truck needs to be adjusted to match the mixrequirements of the concrete article at Jobsite B. An electronic ticketis issued as soon as the concrete delivery truck is confirmed to deliverto Jobsite B. A processor accessible by the concrete delivery truckreceives the delivery time from Plant 2 to Jobsite B. This can be basedon, for example, the time of the last delivery, an average of severalpast deliveries, or a forward prediction of the next delivery. Theprocessor also receives a time estimate for the current concretedelivery truck to reach Jobsite B including time already traveled and anestimate of the time required to adjust the mix design in the concretedelivery truck, which will involve batching at a given plant. At thispoint, the processor is programmed to consider two alternatives. Thefirst alternative is for the concrete delivery truck to return to Plant1, adjust the mix and travel to Jobsite B. The second alternative is forthe concrete delivery truck to travel to Plant 2, adjust the mix, andtravel to Jobsite B.

For the first alternative, the total time between Plant 1, Jobsite A,back to Plant 1 and Jobsite B [via routes 110, 110 and 112] is45×2+25=115 minutes (excluding time to adjust the mix design). The timedifference between this travel time and the time estimate between Plant2 and Jobsite B is 115−10=105 minutes. Thus, a retarder is required.Within this alternative, at Jobsite A, the concrete will be dosed(automatically or manually) with a retarder to adjust for the 105minutes. Once the concrete delivery truck is adjusted at Plant 1, theadditional materials added can be dosed with a retarder to cover thetravel time between Plant 1 and Jobsite B. The entire dosage may beadded at Jobsite A.

For the second alternative, the total time between Plant 1, Jobsite A,Plant 2 and Jobsite B [numbers 110, 116 and 114] is 45+6+10=61 minutes,neglecting the time to adjust the mix design. The time differencebetween this travel time and the time estimate between Plant 2 andJobsite B is 61−10=51 minutes. Again, a retarder is required. In thiscase, however, if retarder is dosed to account for the time betweenPlant 1, Jobsite A and Plant 2 (including any time required to adjustthe mix design), no further adjustment is required since the remainingleg of the trip is the same as deliveries made directly between Plant 2and Jobsite B.

In the above examples, the time to adjust the mix design was notincluded for sake of simplifying the time difference calculations. Ifthe mix design is to be adjusted, then those of ordinary skill in theart based on the disclosures herein will understand how to adjust thetime to compensate for correct age of the concrete. For both thesecases, a “dribble dose” may be used. Thus, instead of measuring theexact dosage of retarder, sufficient retarder is added to take effectfor a certain period of time, e.g., 15 minutes. After this period oftime expires, if more retarder is required, another dose is added, andso on. This is discussed and illustrated in Example 5.

While the embodiments disclosed herein are described herein using alimited number of embodiments, these specific embodiments are notintended to limit the scope of the invention as otherwise described andclaimed herein. Modifications and variations from the describedembodiments exist. More specifically, the following examples are givenas a specific illustration of embodiments claimed. It should beunderstood that the embodiments are not limited to the specific detailsset forth in the examples. All parts and percentages in the examples, aswell as in the remainder of the specification, are by percentage dryweight unless otherwise specified.

Example 1

FIG. 10 graphically illustrates experimental optical measurements of aconcrete slab over time. A concrete mix containing 564 pounds per cubicyard (lbs/yd³) of cement, 1700 lbs/yd³ of stone, 1425 lbs/yd³ of sand,300 lbs/yd³ of water and 7.5 ounces per hundred pounds of cementitiousmaterials (oz/cwt) of WRDA® 64, a low-range water reducer (LRWR). Theconcrete was mixed according to the following protocol: at high speed,the stone, sand, and 80% of the water was mixed for 2 minutes; cementwas added with the remaining water and mixed in at high speed for 2minutes; the LRWR was added and mixed in at high speed for 2 minutes;the mixer was turned off and the concrete was left to rest for 3minutes; and the mixing resumed at high speed for 3 minutes. Aftermixing, a portion of the concrete was tested for slump and air, whilethe remaining concrete was poured into a 2-foot by 3-foot by 6-inchslab, screeded, and hand floated. After this, images were acquired every5 minutes from a stationary camera (which is envisioned to be replacedby a UAV in accordance with embodiments disclosed herein). From eachimage, the mean, median and standard deviation of the grey level wasdetermined using typical image analysis tools (See e.g., Solomon, C. andBreckon, T., Fundamentals of Digital Image Processing: A PracticalApproach with Examples in Matlab, Wiley-Blackwell).

From top to bottom, the following values are plotted over 90 minutes inFIG. 10: the ratio between the median and mean, the median, the standarddeviation. This data helps the formulation of a mathematical model. Inthis case, a generalized logistics function was fit using standardregression tools. Using these equations, the time when the water sheendisappears from the concrete surface for a given concrete section can bepredicted, thus giving the contractor the ability to know when to moveto the next section to finish. As previously mentioned, measurementssuch as this example can be made using an UAV-based sensor, and incombination with the ability to automatically collect measurementsacross the slab over time, can enable contractors to have greaterunderstanding of the set time behavior of the concrete to ensure properfinishing.

Example 2

A second concrete was prepared and mixed in the same manner asExample 1. The mix design was altered to 625 pounds per cubic yard(lbs/yd³) of cement, 1700 lbs/yd³ of stone, 1450 lbs/yd³ of sand, 300lbs/yd³ of water and 4.5 ounces per hundred pounds of cement materials(oz/cwt) of ADVA® 190, a high-range water reducer (HRWR). A 2-foot by2-foot by 6-inch slab was created in the same way as Example 1, and wasalso monitored over time by a stationary camera (again, envisioned to bereplaced by a UAV-based sensor). Different from Example 1 was thelocation of the slab, which was put in an area where lighting wasvariable (e.g., cloud/sunlight changes). In FIG. 10, the medianintensity for each image is shown over time. In this example, there is apoor indication of trends over time. However, a texture analysisalgorithm (See e.g., Machine Vision, R. Jain, R. Kasturi, B. Schunck,pp. 236-238, incorporated herein by reference) can be used to improvecorrelation of sensor data to set time values of the concrete.

As graphically illustrated in FIG. 11, the contrast analysis results aremuch clearer than those shown by using just median intensity.Furthermore, the minimum, which is a characteristics of the curve, canbe correlated to the time for beginning the power floating process.

Example 3

The same concrete samples observed by the stationary camera in Example 2above were observed using a near-infrared sensor, sensitive to the wavelengths in the range of 750-1000 nm. As shown in FIG. 12, after about150 minutes, the sensor readings began to decrease in a linear fashion.This corresponds to the minimum for the contrast of the grey-levelco-occurrence matrix in Example 2. Consequently, this change in behaviorcan be used to provide an indication or signal as to when the powerfloating can begin.

Example 4

Pre-pour data. A system can be programmed to collect data from eachconcrete delivery. First, batch weights, which include the amounts ofcement, aggregates, water and admixtures, are recorded and stored in adatabase. The batch time is also added to the database. The temperatureof the materials can also be added to the database. During the delivery,any water or admixture added to the concrete delivery truck is added tothe database. At the point of discharge, the final concrete temperature,the current ambient temperature, slump (or slump flow), air content(e.g. from a sensor such as commercially available under the CiDRA®brand), drum revolutions, time from batch and concrete volume arerecorded. All data up to this point can be considered pre-pour data. Tosimulate this, 29 concrete mixes were tested in the lab. The same basicmix design was used, which includes 565 pounds per cubic yard (pcy) ofan ASTM Type I cement, 1700 pcy of coarse aggregate, 1425 pcy of fineaggregate, and water that varied between 260 and 300 pcy of water. Ahigh-range water reducer (HRWR) (e.g., ADVA® 198 water reducer from GCPApplied Technologies) was used at 4.00 ounces (oz) per 100 pounds ofcement (cwt), while an air entraining agent (e.g., DAREX®II AEA alsofrom GCP) was used at 0.4 oz/cwt. All mixes were mixed using thefollowing protocol: 1) all of the coarse and fine aggregate was placedin the mixer with 20% of the water and the air entrainer; 2) mix at ahigh speed for 1 minute; 3) add the cement and mix again at high speedfor 2 minutes; 3) add the HRWR while continuing to mix for another 2minutes; 4) stop the mixer and rest for 3 minutes; 5) resume mixing at ahigh speed for 2 minutes; 6) reduce speed and mix for another 1 minute;and finally 7) stop mixer and begin testing. Of the 48 mixes: 9 mixesdid not have AEA; the curing temperature was 2° C. for 8 mixes; and thecuring temperature was 38° C. for 8 mixes. For the remaining 23 mixes,the curing temperature was 20° C. Each mix was tested for pre-pour data:slump and air content.

Post-pour data. The system also records data after the pour. To simulatethis, for each mix tested for pre-pour properties, post-pour propertieswere also tested including initial set time, final set time and strengthat 1, 3, 7 and 28 days. The initial and final set times were estimatedby analyzing the temperature evolution of 4×8 inch cylinders usingtypical methods (e.g.www.intrans.iastate.edu/research/documents/research . . ./CalorimeterReportPhaselll.pdf). All data was recorded in a database.

Based on the pre and post pour data, a random forest model was developedto predict final set time was developed. The data was split into atraining set (29 mixes) and a testing set (19 mixes). Both sets includedsamples with different AEA contents, water contents and curingtemperatures. A random forest model (e.g. seehttps://en.wikipedia.org/wiki/Random_forest) analysis was used todevelop the model shown in FIG. 13, where the x-axis is the actual settime and the y-axis is the predicted set time. The line of equality isplotted along with the predicted points for the testing set. The modelwas developed using pre-pour properties: slump, air, water content, aswell as the curing temperature. This curing temperature can bedetermined using current and near-future weather conditions at the poursite. Thus, data from a weather application can be used to calculatecuring temperature.

It is noted that a variety of methods can be used to develop the model.As copies amounts of data will arise, machine learning techniques wouldbe applicable, including supervised learning (e.g. support vectormachines, Bayesian methods, random forest methods, etc.) andunsupervised learning (k-means clustering, neural networks, etc.). Thiswill be especially suitable when considering more than one mix design.Thus, inputs for the model can be batch weights of each constituent inaddition to what was used in this example.

With the developed model, set time predictions can be made based onpre-pour information from a concrete load, and these predictions caninclude slump, air, water content and curing temperature values or valueranges.

Predicted set time values can be compared with the set times of theconcrete already placed. To coordinate the set times of concrete loads,the difference between predicted and placed set times (based on anyother time required before pouring the concrete) can be set as an inputto a model that calculates appropriate set retarder dosages, forexample. These models take a set time adjustment as an input (e.g. 30more minutes) and outputs a retarder dosage (e.g. 3 oz/cwt). Concreteproducers typically use set retarders to adjust set time of mix designs(but usually retarders are only added at the batch plant); butnevertheless this general understanding of dosage and set timeadjustment exists and is believed by the present inventors to be readilyadapted for intransit/delivery pour methods of the present invention. Assuch, a standard model can be used for all mixes, but it is envisionedthat as more data is collected (e.g. dosages administered and resultingmeasured set time adjustments), the models arising from implementationof the teachings of the present invention can be refined with increasedamounts of data collected. Furthermore, additional inputs to the modelcan be used such as the mix design, batch weights, and pre-pour data(e.g. slump, air). Again, the problem lends itself to resolution throughmachine learning techniques.

After the set retarder dose is calculated, it can be administered intothe concrete drum in order to coordinate the set times.

Example 6

The data of Example 5 was reanalyzed using a “difference” method insteadof an absolute method. That is, instead of predicting the set time basedon the absolute values of temperature, slump, air, water content, adifference between a particular mix and a reference mix was analyzed. Arandom forest model was developed using the same method as in Example 5,and the results are shown in FIG. 14 where the x-axis is the actual settime and the y-axis is the predicted set time. The line of equality isplotted along with the predicted points for the testing set. Again, acorrelation is evident, and would be improved with a larger dataset. Asin Example 5, the predictive model can be used to determine a set timeand thus a set time difference.

Example 7

Same mix design of previous example. Mixing protocol: 1) all of thecoarse and fine aggregate was placed in the mixer with 20% of the waterand the air entrainer; 2) mix at a high speed for 1 minute; 3) add thecement and mix again at high speed for 2 minutes; 3) add the HRWR whilecontinuing to mix for another 2 minutes; 4) stop the mixer and rest for3 minutes; 5) resume mixing at a high speed for 2 minutes; 6) reducespeed and mix for 22 minutes to simulate travel to a jobsite; 7) removalof 0.25 cubic feet of concrete to simulate a partial discharge; and 8)an additional 15 minutes of mixing at load speed. Three scenarios werecompared: 1) no addition of Recover®, a hydration set retarder; 2) aone-time dose of Recover® immediately before mixing after the 0.25 cubicfoot discharge; and 3) three or four incremental dosages (i.e.“dribbled-in”), that total the one-time dose. After mixing, the slump,air, strength and set times were measured. Set times were estimated byusing a fractions method in analyzing semi-adiabatic temperature data ofthe concrete. The time corresponding to the temperature gain that is 21%of the maximum temperature was used for the initial set and the timecorresponding to the temperature gain that is 41% of the maximumtemperature was used for the final set (see e.g.http://www.nrmcaevents.org/?nav=download&file=541).

Two different dosage levels were tested. Within each level, both thedribbled-in and one-time dose had exactly the same total dosage. Thefirst dosage level was tested at 1.0 oz/cwt. For the dribbled-inscenarios, 4 tests were performed with an average of an 82 minuteincrease in initial set compared to a mix without any Recover®. Thestandard deviation was 24 minutes. For the one-time dose scenario, 3tests were performed with an average of a 32 minute increase in initialset compared to a mix without any Recover®. The standard deviation was27 minutes. It is surprising that an incremental dosage scheme provideda more consistent and larger retardation effect, as one would expect alarger, early dosage of Recover would provide the largest retardationeffect.

At a 4.73 oz/cwt dose, 2 tests were performed for each scenario. For thedribbled-in scenario, the average increase in initial set time was 286minutes, while the one-time dose scenario was 289 minutes. The standarddeviations were 7 and 16 minutes respectively. Thus, at higher dosages,the difference between the two scenarios decreases. Thus, depending onthe dose required, an incremental or dribbled-in scheme may bepreferred.

Embodiments disclosed herein are described herein using a limited numberof illustrative embodiments not intended to limit the scope of theinvention as otherwise described and claimed herein.

What is claimed is:
 1. A method for coordinating delivery of concrete,comprising: (A) providing at least two delivery trucks, each having amixer drum containing a concrete load and a processor-controlled systemfor monitoring rheology and at least one set time value or value rangeof the concrete load in the drum, the processors programmed to performfunctions comprising: i. accessing at least one stored set time value orvalue range assigned to concrete loaded in the mixer drum for deliveryto a job site; ii. calculating at least one current set time value orvalue range for the load based on monitored hydration over time; andiii. comparing the at least one stored set time values or value rangeswith the calculated at least one current set time values or valueranges; and (B) adjusting current set time value(s) or value range(s) byintroducing a set accelerator, set retarder, or mixture thereof into atleast one of the at least two delivery truck concrete loads toeffectuate or to modify the sequential placement, finishing, demolding,formwork removal, or compressive strength phases of the concrete loadspoured from the at least two delivery trucks.
 2. The method of claim 1wherein, in step (A), at least three delivery trucks (and morepreferably at least six trucks) are provided, each having a mixer drumcontaining a concrete load and a processor-controlled system formonitoring rheology and set time value or value range of the concreteload in the drum, the processors perform functions (i), (ii), and (iii);and adjust the stored set time value or value range or the current settime value or value range of the concrete.
 3. The method of claim 1wherein both the stored set time value or value range and the currentset time value or value range are adjusted.
 4. The method of claim 1wherein the stored set time value or value range is calculated based onfactors which include the estimated age of the concrete at pour time. 5.The method of claim 1 wherein set time values or value ranges are chosenfrom time values for (a) initiation of finishing; (b) completion offinishing; (c) removing formwork or mold from the concrete; (d) allowingfoot traffic or car traffic on the concrete; (e) releasing tensionedcables from jacks (as used in pre-stressed concrete applications); (f)anchoring or grouting post-tensioned cables (as for post-tensionedconcrete); or (g) casting further concrete on top of previously pouredconcrete.
 6. The method of claim 1 wherein the stored set time value orvalue range accessed by, or accessed and adjusted by, at least one ofthe delivery truck processor-controlled systems is derived from (a)ticket information provided by a batch plant which sourced the concretein the truck mixer drum; (b) foreperson at job site where concrete fromthe truck mixer drum is to be poured; (c) a processor that receives datasignals from humidity, moisture, and/or temperature sensors embeddedwithin, positioned against the surface of, or embedded within concretepoured or placed at the job site or another job site; or (d) a processormonitoring of another concrete delivery truck having aprocessor-controlled system for monitoring rheology and set time valueor value range of the concrete load.
 7. The method of claim 1 furthercomprising adjusting the at least one stored set time value or valuerange, and providing a report or indication of adjustments made to theat least one stored set time value or value range.
 8. The method ofclaim 1 wherein the current set time value or value range is compared tostored set time value or value range in terms of at least one factorchosen from temperature of concrete, rate of temperature change in theconcrete, batch amounts or mix design of the concrete, adjustments inwater or chemical admixture added into the concrete load, rheology, orother property of the concrete.
 9. The method of claim 1 wherein atleast one of the concrete loads in one of the at least two deliverytrucks is returned concrete, and further wherein the comparison ofstored and current set time values or value ranges includesconsideration of the age of concrete from the initial batching of theconcrete which was returned from the job site.
 10. The method of claim 1wherein a first concrete load from a first delivery truck is poured intoplace, and a second concrete load from a second delivery truck is pouredon top of the first concrete load while the first concrete load is in aplastic state, and wherein the first load and second load haveoverlapping set time values or value ranges.
 11. The method of claim 1wherein the stored set time value or value range for concrete previouslydelivered and placed at the job site is obtained or derived from datasignals generated by at least one sensor in the nozzle, hose, or otherconduit of concrete during deposition or spraying of the concretethrough the nozzle, hose, or conduit at a job site.
 12. The method ofclaim 1 wherein a portion of the concrete load in at least one of thedelivery trucks is poured at a first job site, and, within fifteenminutes and more preferably within ten minutes of the pour, a dose ofset retarding agent is introduced into the remaining portion of theconcrete load in the delivery truck, and the remaining portioncontaining the dose of set retarding agent is transported by thedelivery truck to a second job site and poured into place at the secondjob site.
 13. The method of claim 1 wherein at least five (and morepreferably at least ten) delivery trucks are provided in accordance withstep (A) having concrete loads whose set time values or value ranges areadjusted in accordance with step (B), said adjustments being made usingset time value or value range calculations based on signal data obtainedor derived from at least one sensor for monitoring hydration over timeof placed concrete at the job site.
 14. A method for monitoring set timeconditions of a plurality of concrete placements, comprising: movingover a plurality of concrete placement locations at a job site at leastone aerial drone having at least one sensor for monitoring hydrationover time of the placed concrete to obtain data signals indicative ofhydration; comparing the obtained data signals with previously storeddata signals to obtain set time values or value ranges correlated withthe hydration over time data obtained from the at least one sensor; andgenerating a pictorial diagram or map of the plurality of concreteplacement locations along with set time values or value ranges, orsuggested sequence priorities based on set time values or value ranges,thereby to provide indication of placements that are amenable tosequential treatment with respect to (a) initiation of finishing; (b)completion of finishing; (c) removing formwork or mold from theconcrete; (d) allowing foot traffic or car traffic on the concrete; (e)releasing tensioned cables from jacks; (f) anchoring or groutingpost-tensioned cables; or (g) casting further concrete on top ofpreviously poured concrete.